It was an inevitable declaration, a revision that fundamental physics was going to extort from Gordon Moore sooner or later. Silicon-based computers can't continue to double in speed every two years forever. Moore, who laid out that remarkably accurate roadmap 35 years ago, concedes to that point.
"Chip doubling will go from every couple of years to five years," he said without hesitation.
The revision is necessary. Experts in the semiconductor industry believe there are only about 10 to 15 years left before chipmakers run out of ways to pack more transistors on chip, the technique to make chips faster.
Experts know the numbers they use are speculative. High pointed to a 1989 research paper project that looked ahead at what microprocessors might look like today. "At that time, they worked at 25 to 40 MHz," he said. "The prediction was they would reach 250 MHz by 2000, but here we are, at the threshold of 2 GHz," eight times faster than the vision of 11 years ago. If scientists lose miniaturization as tool to boost chip speeds, Moore believes new ways to speed up silicon chips will be found. "We will have to push technology as far as we can by shrinking, then we will start making bigger chips," he said. Chip engineers still face some difficult problems in getting there. As transistors get smaller, they need a high concentration of chemical impurities added to the wafer to help hold an electrical charge called dopants but, at high concentrations, dopants clump together and become electrically inactive. Engineers still have to solve this challenge. Fluctuations in dopant concentration are also a factor. Chips with larger transistors are unaffected, but as transistors get smaller, they become more susceptible and could behave unpredictably. And then, there are "gates", the tiny barriers - one or two nanometers - controlling the flow of electrons in a transistor. A gate denotes whether a chip counts one or zero. An open gate lets an electron through as zero. A closed gate blocks it to count as one. This is the basis for binary math, the engine for all computer calculations.
